The present invention relates to system for cooling the compressor of a gas turbine engine and to supply air to the clearances between the rotating and stationary parts of the compressor.
Modern gas turbine engines, particularly those utilized in aircraft applications, are using higher and higher air temperatures at the compressor outlet in order to increase the power and efficiency of the gas turbine engine. The air temperatures are often at the limit and sometimes beyond the temperature limits for the elements which come into contact with the air. This is particularly true with the peripheral grooves defined by the rotor wheels in which turbine blades are mounted, especially at the downstream stages of the axial compressor.
It is also known to provide clearances between the rotating and stationary portions of the gas turbine engine and to provide labyrinth seals between these elements in order to increase the efficiency and to provide maximum thrust for the gas turbine engine. Systems are also known for adjusting the radial clearances between the rotating and stationary portions of the engine. U.S. Pat. No. 4,849,895 discloses such a system which utilizes real-time adjustment for adjusting the radial clearances between the gas turbine engine rotor and stator as a function of flight conditions of the aircraft. The system utilizes an air flow regulating valve which is controlled by a computer.
Systems are also known for cooling portions of the gas turbine engines. U.S. Pat. No. 4,254,618 discloses turbine cooling system utilizing an air/air heat exchanger. This system is incorporated into a turbofan engine in which the cooling air circulating through the heat exchanger is tapped from the cold flow bypass duct and is utilized to cool a portion of the hot air flowing through the gas turbine compressor. The cooled air is subsequently applied to the compressor.
French Patent 2,485,632 discloses a rotor wheel/blade root structure which facilitates the passage of air between these elements in order to cool the blades and the peripheral groove of the rotor wheel.
Systems are also known to cool the air of the primary air flow circulating in the compressor. French Patent 2,482,196 describes a heat exchanger mounted between a low pressure compressor and a high pressure compressor with air being tapped from the bypass flow. The heat exchanger in this case is used to cool the primary air flow and to heat the bypass air flow. This design allows combining the thermodynamic gain of the intermediary cooling of the primary flow with the propulsive gain linked to heating the bypass flow.